Cooling gas system for dynamoelectric machines



Nov. 25, 1958 w. L. RINGLANVD 2,852,121 COOLING GAS SYSTEM FOR DYNAMOELECTRIC MACHINES Filed Nov. 14, 1955 2 Sheets-Sheet 1 Ll. hmg imm Mme/ NOV. 25, 1958 w, RlNGLAND 2,862,121

COOLING GAS SYSTEM FOR DYNAMOELECTRIC MACHINES Filed NOV. 14, 1955 2 Sheets-Sheet 2 119mm I. @(AMQXW 1) a I MAM United States Patent 9 COOLING GAS SYSTEM FOR DYNAMOELECTREC MACHINES William L. Ringland, West Allis, Wis., assignor to Allis- Chalmers Manufacturing Company, Milwaukee, Wis.

Application November 14, 1955, Serial No. 546,686

4 Claims. (Cl. 310-57) This invention relates to a ventilating arrangement for a gas cooled dynamoelectric machine and more particularly to an improved ventilating duct arrangement for such machines having a fan and a cooler at each end of the machine in which a portion of the cooling gas interchanges ends of the machine such that each cooler contributes to the cooling of the entire machine.

In a conventional gas cooled dynamoelectric machine having a cooler and fan at both ends of the machine, cooling gas is forced into the air gap by the fans from both ends of the machine; it flows through ventilating passages in the stator, and returns tothe coolers and fans for recirculation. Because both'fans are of substantially equal strength, the gas normally returns to the same end of the machine and the same fan which caused it to flow in'tothe air gap and through the ventilating passages. Thus, conventional ventilating arrangements comprise substantially two separate systems, one for each end of the machine with little interchange of cooling gas from one end of the machine to the other, and each cooler contributes to the cooling of only half of the machine.

This prior art arrangement has the disadvantage'in that in the event one of thecooler's is disabled or shut down for cleaning the remaining 'cool'er' would providecooling for only one end of the machine, and th'e: machine would have to be shut down to prevent the otherend' from'ov'erheating.

Ventilating arrangements have been suggested in which cooling gas passes at least partly tooppo'site ends of the machine; however, these arrangements create a complex flow of cooling. gas through the machine and thus add friction to the flow and increase the power" required to drive the fans.

According to the present invention, collectionducts are arranged axially of the machine and extend substantially from one end of the stator core to the other. These ducts are provided around the circumference of the stator core and receive cooling gas forced into the air gap from both ends of the machine as thegas discharges from ventilating passages of the stator. This arrangement of the collector ducts permits some of the cooling gas discharged into the air gap by both fans to be collected in each duct. Hood means are arranged at one end of one group of collector ducts so that cooling gas collected therein can flow only to a cooler and fan at a first end orthe machine. Similarly, hood means are arranged at the other end of a second group of collectorducts so that cooling gas collected therein can flow only to a cooler and a fan at a second end of the machine. Thus, a portion of the cooling gas is caused to interchange ends of the mashing some gas discharged by each fan is caused to pass through the coolers at both ends of the machine, and each cooler will contribute to the cooling of the entire machine.

It is therefore an object of this invention to provide an improved ventilating. arrangement for a dynamoelectric machine.

Another object of the-presentinvention is to provide 2,862,121 Pat-tented Nov. 25, 1958 2 a ventilating arrangement for a dynamoelectric machine in which each of two coolers will contribute to thecooling of the entire machine.

Another objectof the inventionis toprovide a ventilating arrangement for a dynamoel'ectric machine in which disability of one of two coolers Will not forcea shutdown of the machine;

Another object of the invention is to provide a ventil'at ing arrangement fora dynamoelectric machine in which the resistance to flow of the cooling gas is kept at a minimum. g I

Objects and advantages-other than those above s'tate d will-be apparent from the following description when read in connection with the accompanying drawings,in which:

Fig. 1 is a longitudinal sectional view" of a dynamic- "ice . electric machine embodying the invention;

Fig. 2 is a transverse sectional view taken alongline II-II of Fig. 1; and

Fig. 3 is a developed view of the collecting duets with the outer wrapper removed and the how of cooling gas indicated.

Referring to-' the drawings, the invention is shown providing'a ventilating arrangement for adynamoelectric machine 5 which includes a housing It) comprising a wrapper 11, end pieces 12' and 13 and cap 14 enclosing an exciter (not shown). Housing 10'cont'ainsa cooling gas which is preferably a light weight gas such as hydrogen.

A- rotor 20', which comprises a rotatable shaft 21, core element 22 mounted in shaft 21 and windings 23 wound on the core elements, is rotatably mounted by bearing assemblies 24 and 25.

A stator 39, which comprises an inner wrapper 35 and core 31- having winding 32 positioned in slots therein, surrounds rotor 20 and forms an air gap 33 therebetween; Radial ventilating passages 34 are provided in the core 31 and extend from air gap 33 to the outer periphery of the stator core. Inner wrapper 35 is provided around the periphery of the stator core, and ports 36 are provided in the inner wrapper 35 to permit passage of cool ing gas flowing through the ventilating passages 34 to pass through the inner wrapper 35.

Means are provided for forcing cooling gas into the air gap from both ends of the rotor and circulating the gas through ventilating passages 34 of the stator. These means comprise fans 38- whichare attached to rotatable shaft 21 and driven thereby. Fans 38 may also be arranged to draw air from the air gap 33 and to circulate cooling gas in the opposite direction through ventilating passages 34.

Inner wrapper 35 is spaced from and rigidly positioned with respect to outer wrapper 11 by suitable means which are shown as comprising end plates 45 and bracing plates 46 rigidly secured in any convenient manner, as by welding, to the inner and outer wrappers. End plate 45 and bracing plates 46 extend circumferentially around stator core 31. Finger brackets 47 engage end plates 45 and stator core 31 and cooperate with bolts 48 to axially secure core 31 within the inner wrapper 35.

Means are provided for collecting cooling gas discharging from the stator ventilating passages 34 through ports 36 in inner wrapper 35. These means comprise collecting ducts 49' which are positioned around the circumference of the stator core and extend axially of the machine for substantially the length of the stator core. The collecting ducts are formed by partitions 50 and ports 51 cooper ating with inner wrapper 35 and outer wrapper 11. Pairtitions 50 are spaced around the circumference of the stator 30 andextend from the inner wrapper 35 to the outer Wrapper 11 and substantially from one end to the other end of the stator core 31. These partitions may be skewed with respect to the axis of the stator but are preferably axial of the stator, as shown.

Ports 51 are positioned in end plates 45 and bracing plates 46 such that cooling gas may flow axially of the dynamoelectric machine through collecting ducts 49. These ports are of sufiicient size to provide a free flow of cooling gas through the collecting ducts with the minimum of resistance to the flow of cooling gas.

, Means are provided at both ends of machine 5 for returning the gas from the collecting ducts 49 to the fans 38 and 'for cooling the gas. Such means may comprise, as shown by Fig. 1, return ducts 55, coolers 65 and fan intake chambers 75.

Coolers 65 comprise nested tubes 66 supported by a housing 71 formed by plates 67, 68, 69 and 70 around thetubes. Tubes 66 are connected to a suitable source of cooling means (not shown). Plates 67 and 68 contain openings 72, 73, respectively, to permit cooling gas to flow through the housing 71 and around the nested tubes 66.

Return ducts 55 are formed at both ends of machine 5 by the end portions of the inner Wall of housing cooperating with inner partitions 74. The inner partitions 74 comprise circumferential plates 56 and 58 and radial plates 57 and 59 at respective ends of the machine. Radial plate 59 is intersected by and joined to cap 14 housing the exciter (not shown) so that cooling gas flows around the cap and does not bypass the cooler at that end of the machine. Inner partition 74 is connected to end plates 45 and to housing 71 by suitable means as by welding to connect return ducts 55 with ports 51 in the end plates and with opening 72 of the housing 71 enclosing the nested cooling tubes 66.

Fan intake chambers 75 comprise the inner Wall of the inner partitions 74, circumferential partitions 76 and radial partitions 77 which are attached to circumferential partitions 56 and 58, respectively, to form intake chamber 75 at both ends of the machine. Circumferential partitions 76 form a fan intake housing for fans 38.

Means are provided for closing a first group of collecting ducts to passage of gas from the first group to return duct 55 at a first end of the machine and for closing a second group of collecting ducts to passage of gas from the second group to return duct 55 at a second end of the machine. These means may comprise partitions positioned in the collector ducts 49 at any convenient angle at an end of the collector ducts, but preferably they comprise hoods 80 positioned at an end of the collecting ducts 49 so that they close an end thereof. The hoods 80 are shown positioned at opposite ends of adjacent collecting ducts. Thus, it will be seen that alternate collecting ducts form first and second groups of collecting ducts which are closed to passage of gas to return ducts 55 at first and second ends, respectively, of the machine. Although hoods 80 are preferably positioned at alternate ends of adjacent ducts 49, they may also be positioned at the ends of any other series or combination of collecting ducts to form first and second groups.

In order to keep the resistance to the flow of cooling gas to a minimum without increasing the size of the machine, means are provided to permit uniform spacing of ports 51 around the entire surface of end plate 45. These means include openings .85 which permit cooling gas flowing in one collecting duct to pass over the outer surface of the hoods 80 and flow through the uniformly spaced ports in the end plates. By this arrangement, the area in the end plate which is available for ports is greatly increased and the resistance to the flow of cooling gas from the collecting ducts 49 to the return ducts is held to a minimum.

In the operating of the ventilating system, fans 38 force cooling gas into the air gap 34. The cooling gas flows through the radial ventilating passages 33 for the stator core and through ports 36 in the inner wrapper to the axially extending collecting ducts 49. Because collecting ducts 49 extend axially of the core and are positioned around the circumference of the core, a portion of the cooling gas discharged by both fans is collected in each of the collecting ducts. As hoods close alternate ends of alternate ducts and form first and second groups of collecting ducts, the cooling gas in alternate collecting ducts can only flow to return ducts 55 at opposite ends of the machine. The gas flows through the return ducts 55 at each end of the machine, hence through housings 71 and coolers 65 where the gas is cooled. From the cooler 65 the gas flows to intake chambers 75 and returns to fans 38 to be recirculated. In flowing from the collecting ducts 49 to the return ducts 55, the gas may flow through ports 51 axially aligned with the open ends of the collecting ducts or may flow through openings then over hoods 80 and through ports 51 axially aligned with the closed ends of the collecting ducts.

It may now be seen that according to the present invention each cooler contributes to the cooling of the entire dynamoelectric machine; and that continued operation of the dynamoelectric machine is possible with the present arrangement even though one of the two coolers is not functioning.

While but one embodiment of the invention has been both shown and described, other embodiments or arrangements will be apparent to one skilled in the art without departing from the spirit of the invention or from the scope of the appended claims.

It is claimed and desired to secure by Letters Patent:

1. A totally enclosed dynamoelectric machine comprising, a housing, a rotor, a stator core spaced from said housing and forming an air gap with said rotor, means forming ducts between said core and said housing, said ducts extending axially of said stator core, said stator core having radial ventilating passages connecting said air gap to said ducts, means positioned at one end of a first group of said ducts closing said end to passage of gas, means positioned at the opposite end of a second group of said ducts closing said end to passage of gas, fans at both ends of said machine forcing cooling gas axially into said air gap and through said radial passages to said ducts to cause each of said ducts receiving gas from both of said fans, means at one end of said machine including a cooler for cooling and returning said gas from said first group of said ducts to said fan at said end of said machine, means at the other end of said machine including a cooler for cooling and returning said gas from said second group of said ducts to said fan at said other end of said machine.

2. A totally enclosed dynamoelectric machine cornprising: a housing, a rotor, a stator core spaced from said housing to form an air gap with said rotor, said air gap having a first end and a second end, means positioned between said stator core and said housing to form a first group of collector ducts and a second group of collector ducts disposed around the circumference of said stator core, each of said ducts extending substantially from one end to the other end of said stator core and axially thereof, a series of radially extending ventilating passages in said stator core connecting said air gap with said ducts, means positioned at one end of said first group of ducts and means positioned at the opposite end of said second group ducts to close said respective ends to passage of gas, said means closing said first group ducts being at said end of said first ducts remote from said first end of said air gap and said means closing said second group ducts being at said end of said second ducts remote from said second end of said air gap, substantially gas tight wall means within said housing forming a first recirculating passage connecting the open ends of said first group ducts to said first end of said air gap and substantially gas tight wall means within said housing forming a second recirculating passage connecting the open ends of said second group ducts to said second end of said air gap, fan means in each of said recirculating passages arranged to force said cooling gas from said ducts into said air gap and radially outward through all of said ventilating passages to said ducts, and gas cooling means in each of said recirculating passages positioned intermediate said group ducts and said air gap ends.

3. A totally enclosed dynamoelectric machine comprising: a housing, a rotor, a stator core spaced from said housing to form an air gap with said rotor, said air gap having a first end and a second end, a series of partitions extending radially and axially of said machine be tween said housing and said stator core to form a first and second group of axially extending collector ducts disposed around the circumference of said stator core, each of said ducts extending axially substantially the longitudinal length of said stator core, said first group ducts comprising alternate ducts and said ,second group comprising said ducts interposed between said alternate ducts, a series of radially extending ventilating passages in said stator core connecting said air gap to said ducts, a hood positioned at one end of each of said first group ducts and a hood at the other end of each of said second group ducts to close said respective ends to passage of gas, said hoods closing said first group ducts being at said end of said first ducts remote from said first end of said air gap and said hoods closing said second group ducts being at said end of said second ducts remote from said second end of said air gap, wall means within said hous ing to form a first recirculating passage connecting the open ends of said first group ducts to said first end of said air gap and wall means within said housing to form a second recirculating passage connecting the open ends of said second group ducts to said second end of said air gap, fan means in each of said recirculating passages mounted at each end of said rotor to force substantially all said gas into said air gap and radially outward through all of said ventilating passages to all of said ducts, and cooling means in each of said recirculating passages positioned intermediate said ducts and said air gap.

4. A totally enclosed dynamoelectric machine comprising: a housing, a rotatable shaft having a rotor mounted thereon, a stator core spaced from said housing to form an air gap with said rotor, partitions extending axially of said machine from said housing to said stator core to form collector ducts disposed around the circumference of said stator core, each of said ducts extending substantially from one end to the other end of said stator core, fans mounted on said rotatable shaft at each end of said rotor adjacent said air gap forcing cooling gas into said air gap of said machine, a series of ventilating passages in said stator core connecting said air gap to said ducts, hood plates at one end of a first group of said ducts and at the other end of a second group of said ducts to close said respective ends to passage of said gas, means connecting the open ends of said first group ducts to a first end of said air gap and means connecting the open ends of said second group ducts to an end of said air gap remote from said first end to form substantially gas tight recirculating passages, said ducts each collecting said gas forced into said ventilating passages by both of said fans to deliver equal portions of mixed gas to said fans for recycling, said ducts each respectively receiving through said ventilating passages substantially percent of the gas forced into said air gap by each fan, and cooling means in each of said recirculating passages interposed between said ducts and said air gap.

References Cited in the file of this patent UNITED STATES PATENTS 1,883,912 Henningsen Oct. 25, 1932 2,650,313 Wiedemann Aug. 25, 1953 FOREIGN PATENTS 511,932 Belgium June 30, 1952 681,077 Great Britain Oct. 15, 1952 820,759 France Aug. 9, 1937 

